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<h1>代码折叠</h1>
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<span id="za">za</span>                  <span>切换折叠</span>
<span id="zA">zA</span>                  <span>递归切换折叠</span>
<span id="zc">zc</span>                  <span>折叠光标下代码</span>
<span id="zC">zC</span>                  <span>折叠光标下所有代码</span>
<span id="zd">zd</span>                  <span>删除光标下折叠</span>
<span id="zD">zD</span>                  <span>递归删除所有折叠</span>
<span id="zE">zE</span>                  <span>删除所有折叠</span>
<span id="zf">zf</span>                  <span>创建代码折叠</span>
<span id="zF">zF</span>                  <span>指定行数创建折叠</span>
<span id="zi">zi</span>                  <span>切换折叠</span>
<span id="zm">zm</span>                  <span>所有代码折叠一层</span>
<span id="zr">zr</span>                  <span>所有代码打开一层</span>
<span id="zM">zM</span>                  <span>折叠所有代码，设置 foldlevel=0，设置 foldenable</span>
<span id="zR">zR</span>                  <span>打开所有代码，设置 foldlevel 为最大值</span>
<span id="zn">zn</span>                  <span>折叠 none，重置 foldenable 并打开所有代码</span>
<span id="zN">zN</span>                  <span>折叠 normal，重置 foldenable 并恢复所有折叠</span>
<span id="zo">zo</span>                  <span>打开一层代码</span>
<span id="zO">zO</span>                  <span>打开光标下所有代码折叠</span>
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